1. Field
The presently disclosed subject matter relates to a vehicle lamp that includes a light source and a casing in which the light source is sealed, and more particularly to a vehicle lamp further including a heat dissipation structure that can prevent the casing and other components from experiencing thermal damage.
2. Description of the Related Art
A vehicle can include various vehicle lamps such as a headlight, a taillight, a stop lamp, a position lamp, a turn-signal lamp and the like, which include a light source such as an incandescent bulb, a halogen bulb, a high-intensity discharge lamp, an LED lamp, etc. Some vehicle lamps include a casing and other components such as a reflector, an outer lens and the like as necessary so that the light distribution thereof can conform to a light distribution standard.
In general, there has been a desire to miniaturize vehicle lamps in order for passengers to maintain a comfortable amount of space and in order to provide space for cargo, engine components, design features, etc. Thus, the casing including the light source, the reflector and the like can be miniaturized. In addition, because the miniaturized casing includes a light source that gives out heat in the small sealed casing, positioning for a heat dissipation structure in the vehicle lamp is a major issue as well as a configuration of the vehicle lamp to conform to a light distribution standard.
Because, if the heat dissipation structure cannot normally operate, the casing and other components such as the reflector may deteriorate, transform and/or tarnish. Accordingly, the vehicle lamp may not be able to conform to a light distribution standard and also may become unable to operate.
An exemplary embodiment of the conventional vehicle lamp including a heat dissipation structure is disclosed in patent document No. 1 (Japanese Patent Application Laid Open H04-004503). FIG. 3 is a schematic side cross-section view showing an exemplary structure of this conventional vehicle lamp. A vehicle lamp 1 shown in FIG. 3 is a rear combination lamp that can include a stop lamp, a taillight, a position lamp, a turn-signal lamp, etc.
The vehicle lamp 1 includes a casing 2, a bulb 3, a reflector 4, a front lens 5 and a heat-insulating board 6. The casing 2 that fixes components of the vehicle lamp 1 is open in a direction towards a light-emission of the vehicle lamp 1. The bulb 3 that is used as a light source for the vehicle lamp 1 is located in the reflector 4. The reflector 4 reflects light emitted from the bulb 3 in the direction towards the light-emission of the vehicle lamp 1.
The front lens 5 is composed of a transparent resin and is attached to the casing 2 so as to cover the front open area thereof. The heat-insulating board 6 is located at an upper portion of the reflector 4. The casing 2 is composed of an opaque material such as a resin, a metal and the like, and seals both the bulb 3 and the reflector 4 with the front lens 5. The reflector 4 is located only around the bulb 3 as shown in FIG. 3, however, the reflector 4 may be actually located around other bulbs for other lamps included in the rear combination lamp.
The bulb 3 can be a halogen bulb and the like, having an optical axis located parallel with respect to the direction of light-emission for the vehicle lamp 1. The bulb 3 is attached to a socket 3a and receives a power supply via the socket 3. The reflector 4 is composed of a resin and the like, and an inner surface thereof is configured with a parabolic surface in order to reflect light emitted from the bulb 3 in a direction towards the front lens 5.
The front lens 5 is composed of a transparent material in order to allow the above-described reflex light to pass in the direction of light-emission of the vehicle lamp 1. The front lens 5 is attached to the casing 2 so as to be able to seal the open area of the casing 2. Therefore, both the casing 2 and the front lens 5 can result in a hermetic inner space for the vehicle lamp 1.
The heat-insulating board 6 is composed of a high thermal conductive material such as a metallic plate and the like. The heat-insulating board 6 is located along an inner surface of the reflector 4 and contacts an upper portion 4b of the reflector 4. The heat-insulating board 6 is attached to the rear of the reflector 4 by screwing a rear end portion 6a thereof with a screw 6b after it is inserted into an inside of the casing 2 from a backward direction of the reflector 4 via a slot 4c, which is located near an upper rear of the reflector 4.
According to the vehicle lamp 1 of the above-described structure, when the bulb 3 receives the power supply and emits light, both the direct light emitted from the bulb 3 and the reflex light reflected from the reflector 4 is emitted ahead in the light-emission direction of the vehicle lamp 1 via the front lens 5.
In that case, heat generated from the bulb 3 produces an increase in temperature of air around the bulb 3 located in the reflector 4. Because the hot air expands and a specific gravity thereof becomes light, the hot air moves upwards in a direction towards the upper portion 4b of the reflector 4. Thus, the hot air heats up the upper portion 4b of the reflector 4.
However, because the heat-insulating board 6 is located underneath the upper portion 4b of the reflector 4, the heat-insulating board 6 can prevent the upper portion 4b from thermal damage caused by the hot air. Thus, the upper portion 4b of the reflector 4 may not deteriorate or transform and/or tarnish due to the heat generated from the bulb 3.
FIGS. 4(A) and (B) are a schematic perspective view and a schematic side cross-section view showing another exemplary structure of a conventional vehicle lamp, respectively. In the following description with reference to FIGS. 4(A) and (B), the same or corresponding elements as shown and described with reference to FIG. 3 use the same reference marks as reference marks used in the above description of FIG. 3, and their operation and description are abridged in the following description.
According to a vehicle lamp 7 shown in FIGS. 4(A) and (B), a pair of ribs 2b is located underneath an upper portion of a casing 2, and a heat-insulating board 6 can be inserted between the pair of ribs 2b from a direction of a front lens 5. Thus, because the heat-insulating board 6 can be sandwiched between the pair of ribs 2b and attached to the casing 2, the heat-insulating board 6 can prevent the upper portion of the casing 2 from thermal damage caused by heat generated from bulb 3.
In the above-described vehicle lamps 1 and 7, because their heat-insulating boards 6 are located underneath the upper portions of the reflector 4 and the casing 2, respectively, the heat-insulating boards 6 may be seen from outside of the vehicle lamps via their front lenses 5. Therefore, their outside appearance may not look very good and/or maybe limited with respect to design creativity.
In addition, when reflectors 4 extend in their upwards directions in order to conform to a light distribution standard, it may be difficult or even impossible to extend these reflectors 4 upwards. Furthermore, if heat-insulating boards 6 receive a part of the light emitted from bulbs 3, this unexpected incoming light may be emitted to the outside via front lenses 5.
In the vehicle lamp 7 shown in FIGS. 4(A) and (B), because the pair of ribs 2b is located underneath the upper portion of the casing 2, when the pair of ribs 2b receives a part of light emitted from the bulb 3, the unexpected light may be emitted to the outside via the front lens 5. Thus, the above-described unexpected light may cause a problem and may not conform to a predetermined light distribution pattern.
In an assembling process of the vehicle lamp 1 shown in FIG. 3, the heat-insulating board 6 is inserted into the inside of the casing 2 from the backward direction of the reflector 4 via the slot 4c. In this case, turnings or shavings may occur due to an edge of the heat-insulating board 6 rubbing against the reflector 4 during insertion and/or from the screw process itself. Similarly, in an assembling process of the vehicle lamp 7, the heat-insulating board 6 is inserted between the pair of ribs 2b from the direction towards a front lens 5 and is fixed at a predetermined position. In this case, turnings or shavings may likewise occur due to an edge of the heat-insulating board 6.
The above-described turnings or shavings may frequently fall down from the slot 4c and the pair of ribs 2b in the reflector 4 and/or the casing 2. Thus, these turnings and/or shavings may cause a defect in the vehicle lamps 1 and 7. Moreover, the above-described heat-dissipation structure cannot basically lose the hot air to the outside of the casing 2 but can lose the hot air in the casing 2. Thus, when the hermetic inner space of the casing 2 is small and the bulb continuously emits for a long time, the vehicle lamp may not be configured properly to prevent the casing 2 and other components from experiencing thermal damage caused by the heat generated from the bulb 3.
The above-referenced Patent Documents are listed below.                1. Patent document No.1: Japanese Patent Application Laid Open H04-004503        
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, an embodiment of the disclosed subject matter can include a vehicle lamp including a light source and a casing in which the light source is sealed, wherein a feature of the vehicle lamp can include providing a heat dissipation structure that can prevent the casing and other components from experiencing thermal damage. The heat dissipation structure can radiate the heat generated by the light source to the outside of the casing while it can be hidden from the outside of the vehicle lamp. In addition, an attachment thereof can be simple. Because the heat-insulating portion of the above-described structure can be used as a reflex surface, the heat dissipation structure can result in a small vehicle lamp having a favorable light distribution.